You need to install ClockworkMod Recovery before you can install a custom ROM. With ClockworkMod Recovery, you can install, backup and restore a ROM. Before following the instructions on this page, make sure you have installed the USB drivers (not required for Mac or Linux)

Instructions for Windows

Open Settings from the app list on your phone.

Tap Applications.

Tap Development.

Make sure USB debugging is ticked.

Tap OK.

With your phone on, connect it to your computer (use the cable included with your phone).

Within a few seconds, your phone will reboot, and a green Android logo will appear. The whole process may take up to 10 minutes. During < waiting for device >, Windows may attempt to download and install a driver. This may take a few additional minutes.

ClockworkMod Recovery successfully installed on the Oranage San Francisco II / ZTE Crescent. You may close the window.

Once completed, your phone will reboot and turn on to its normal state. On your computer, you should see Press any key to continue . . . You may close the window safely.

ClockworkMod Recovery should now be installed on your phone, and you can continue to the next page to install a custom ROM.

Instructions for Mac

Open Settings from the app list on your phone.

Tap Applications.

Tap Development.

Make sure USB debugging is ticked.

Tap OK.

With your phone on, connect it to your computer (use the cable included with your phone).